Romantic Partners Share 44.4% of Mouth Bacteria, More Than Double 19.5% Gut Rate
Updated
Updated · studyfinds.com · Jun 17
Romantic Partners Share 44.4% of Mouth Bacteria, More Than Double 19.5% Gut Rate
3 articles · Updated · studyfinds.com · Jun 17
Summary
1,644 saliva-and-stool sample pairs from 808 people in 207 households showed couples shared oral bacteria at a median 44.4%, versus 19.5% for gut bacteria; parent-child and sibling pairs showed no similar gap.
Kissing and close physical contact likely drive that difference, and oral microbes also changed faster: among 66 adults tracked for about 3.5 months, mouth strains turned over at 14.7% versus 5.8% in the gut.
644 matched oral and stool samples also suggested mouth bacteria regularly seed the gut: when strain-level matches were possible, 74.5% showed the same strain in both sites, including Streptococcus salivarius in 68% of 138 people.
197 gut bacterial species were analyzed, and the 27 most transmissible within households were disproportionately linked to poorer cardiometabolic health, though the study says those associations do not prove the microbes cause disease.
Researchers also identified a distinct oral branch of Bifidobacterium longum, proposing a new subspecies—B. longum subsp. nexti—highlighting that microbial exchange between partners and body sites is more dynamic than previously assumed.